METHOD OF MANUFACTURE OF SEAMLESS PIPES FROM LOW- CARBON STEEL Russian patent published in 2003 - IPC

FIELD: steel metallurgy; manufacture of cold- resistant oil pipes for operation in moist media containing hydrogen sulfide. SUBSTANCE: proposed method is based on use of continuously cast low-carbon steel blank containing no more than 0.005% of sulfur, no more than 0.010% of nitrogen and 0.010- 0.050% of aluminum at ratio of aluminum to nitrogen from 2:1 to 10:1. Hot deformation is carried out at limitation of temperature of end of deformation by range [Ar₃-(Ar₃+100)]C. Heat treatment is performed in one or several stages followed by final high-temperature tempering continued for 30-60 min at temperatures (580-Ac₁)^°C; then pipes are subjected to straightening within temperature range of (550-Ac₁)^°C. EFFECT: enhanced cold resistance and resistance to damage in media containing hydrogen sulfide. 1 tbl, 2 ex